In the past, rehabilitation of movement impairments due to stroke or the like has centered on training in a "slow and accuracy-requiring" movement, such as an insertion of peg, which is done while making corrections using visual and somatosensory feedback information or in a "quick but accuracy-non-requiring" movement.
However, the former training in a "slow and accuracy-requiring" movement tends to stiffen one's arm and leg. The latter training tends not to require accuracy. Consequently, it has been difficult to restore a motor function of a quick and accurate movement of one's arm, leg and the like, which are kept in a compliant and relaxed state, without corrections during their movements.
Such a quick and accurate movement, e.g., a movement of quickly reaching out one's hand to an object or a movement of throwing a ball toward a target, is known as a feedforward-movement. On the other hand, a movement of arranging objects or tracking an object while making corrections using visual or somatosensory information is known as a feedback-movement. The aforementioned "slow and accuracy-requiring" movement is an example of the feedback-movement.
For the feedback-movement, since a feedback controller is used, it is not necessary to create, within one's brain, a dynamics model of a body part such as an arm and a leg. On the other hand, to do the feedforward-movement, it is necessary to calculate a control signal in advance, using a dynamics model of a body part.
If the relation between the control signal and the body part's movement changes due to a movement impairment, the control signal can no longer be calculated correctly using the heretofore used dynamics model of the body part. Therefore, a new dynamics model must be re-created. This is effectively achieved by training the person in the feedforward-movement making positive use of a dynamics model.
Furthermore, restoration of a motor function has been assessed based on a psychological measurement obtained by doctor's observation, i.e., on an ordinal scale, thus an objective and quantitative evaluation based on a physical measurement, i.e., a ratio scale, has not been made.
In view of the foregoing circumstances, the invention of this application has been made, and it is an object of the invention to provide a novel feedforward-movement training apparatus which solves the problems with the prior arts and can realize restoration of functions to do fast and accurate movements in a relaxed state by training the feedforward-movements. It is another object of the invention to provide a novel feedforward-movement evaluating system which objectively and easily evaluates the degree of skillfulness of the patient's feedforward-movements in the feedforward-movement training apparatus and thus can more effectively restore fast and accurate motor functions in a relaxed state.